Share This

The oscillating proton (red) generates a tiny current which is recorded using highly sensitive electronic detectors. The red arrow represents the magnetic moment of the proton; the green lines indicate the magnetic field in the trap.

Related Articles

One of the biggest riddles in physics is the apparent imbalance between matter and antimatter in our universe. To date, there is no explanation as to why matter and antimatter failed to completely annihilate one another immediately after the big bang and how the surplus matter was created that went on to form the universe as we know it. Experiments conducted at Johannes Gutenberg University Mainz (JGU) have contributed towards a resolution of this problem. For the first time a direct and high-precision measurement of the magnetic moment of the proton has been conducted successfully. The magnetic moment is one of the fundamental properties of protons, which combine with neutrons to form the nucleus of atoms. In principal, the method can also be used to measure the magnetic moment of an antiproton with a similarly high precision, making it possible to investigate matter/antimatter asymmetry. Related experiments are now being set up at the CERN research center in Geneva, Switzerland.

Years of preparation were necessary before the measurements were possible and the results obtained have far exceeded those of all previous attempts. In addition to Mainz University, the GSI Helmholtz Center for Heavy Ion Research in Darmstadt, the Max Planck Institute of Nuclear Physics in Heidelberg, and the Japanese RIKEN research facility all took part in the experiment. Using a double Penning trap, the researchers were able to determine the relevant parameter, the so-called 'g-factor,' with a precision of 3.3 x 109. The result is 760 times more precise than all the results documented independently at Mainz University and Harvard University in 2012, and three-times more precise than the result obtained by an indirect measurement in 1972.

"Protons are like tiny rod magnets. They have a magnetic moment 24 magnitudes -- equal to one millionth of a billionth of a billionth -- weaker than a typical compass needle. This is the first time we have been able to measure anything on this scale," said Andreas Mooser, primary author of the study and a member of Professor Jochen Walz's research team at Mainz University. The key to success proved to be the use of a double Penning trap, i.e., an electromagnetic particle trap, to isolate and evaluate a single free proton. An analysis trap serves to detect spin-quantum jumps of the proton, while in a precision trap precise frequency measurements are conducted.

It has proved possible in the past to use Penning traps to directly measure the magnetic moment of individual particles such as electrons and their antiparticle counterparts, positrons. But adapting this approach for use with protons is an enormous challenge as the magnetic moment of a proton is 660 times smaller than that of an electron. The apparatus for the experiment needed to be far more sensitive. The collaborating partners were able to develop such a highly sensitive double Penning trap so that they could undertake the long-planned measurements.

Apart from the direct measurement performed in Mainz, the previous most precise measurements were obtained by means of an indirect method in 1972, where the hyper-fine structure of atomic hydrogen was measured and subsequently theoretical corrections were applied.

The principle of a direct measurement in a double Penning trap can also be used for the antiproton. "We can then compare the two results and test these against the fundamental predictions of the standard model," explained Stefan Ulmer, coordinator of the BASE joint project, which is currently setting up a corresponding experiment at CERN in Geneva.

Using the double Penning trap technique for the antiproton could enhance the precision of results obtained during the ATRAP project in 2013 by a factor of at least 1,000. Assuming that the measured values differ, this would represent an important step forward with regard to understanding the matter/antimatter asymmetry of our universe.

More From ScienceDaily

More Matter & Energy News

Featured Research

Mar. 3, 2015 — By examining the forces that the segments of mosquito legs generate against a water surface, researchers have unraveled the mechanical logic that allows the mosquitoes to walk on water, which may ... full story

Mar. 3, 2015 — Researchers have developed a new way of rapidly screening yeasts that could help produce more sustainable biofuels. The new technique could also be a boon in the search for new ways of deriving ... full story

Mar. 3, 2015 — Major cities in the UK are falling behind their international counterparts in terms of their use of smart technologies, according to a new study. The research has found that smart cities in the UK, ... full story

Mar. 3, 2015 — Scientists have explored friction at the microscopic level. They discovered that the force generating friction is much stronger than previously thought. The discovery is an important step toward ... full story

Mar. 3, 2015 — Micro-drones are already being put to use in a large number of areas: These small aircraft face extensive requirements when performing aerial observation tasks or when deployed in the field of ... full story

Mar. 3, 2015 — Recent research contributes to the effort to determine the nature of dark matter, one of the most important mysteries in physics. As indirect evidence provided by its gravitational effects, dark ... full story

Mar. 3, 2015 — Physicists have shown for the first time that electrons in graphene can be moved along a predefined path. This movement occurs entirely without loss and could provide a basis for numerous ... full story

Featured Videos

Forensic Holodeck Creates 3D Crime Scenes

Reuters - Innovations Video Online (Mar. 3, 2015) — A holodeck is no longer the preserve of TV sci-fi classic Star Trek, thanks to researchers from the Institute of Forensic Medicine Zurich, who have created what they say is the first system in the world to visualise the 3D data of forensic scans. Jim Drury saw it in operation.
Video provided by Reuters

Solar Plane Passes New Test Ahead of World Tour

AFP (Mar. 2, 2015) — A solar-powered plane made a third successful test flight in the United Arab Emirates on Monday ahead of a planned round-the-world tour to promote alternative energy. Duration: 01:05
Video provided by AFP

Electric Hydrofoiling Watercraft Delivers Eco-Friendly Thrills

Reuters - Innovations Video Online (Mar. 2, 2015) — The Quadrofoil is a high-tech electric personal watercraft that its makers call a &apos;sports car for the water&apos;. When it hits 10 km/h, the Slovenian-engineered Quadrofoil is lifted above the water onto four wing-like hydrofoils where it &apos;flies&apos; above the surface with minimal water resistance. Matthew Stock reports.
Video provided by Reuters

Related Stories

May 28, 2014 — As part of a series of experiments designed to resolve one of the deepest mysteries of physics today, researchers have made the most precise ever direct measurement of the magnetic moment of a ... full story

July 28, 2011 — The Japanese-European ASACUSA experiment at CERN has reported a new measurement of the antiproton's mass accurate to about one part in a billion. Precision measurements of the antiproton mass ... full story

June 21, 2011 — An important milestone in the direct measurement of the magnetic moment of the proton and its anti-particle has been achieved. Researchers have observed spin quantum-jumps with a single trapped ... full story

ScienceDaily features breaking news and videos about the latest discoveries in health, technology, the environment, and more -- from major news services and leading universities, scientific journals, and research organizations.